I googled, hoping to find a step-by-step guide but haven't been able to yet. Video Card ATI Radeon HD 2600 XT 256 MB Mac Pro Early 2008 A1186 NB-2155W. It seemed like someone said I had to get some sort of power adapter for these cards if I buy a PC card? Looks like it's included with macvidcards' cards. Will there be a performance boost for doing so? Will I need more power? Will this work in Windows? I'm not sure, but it seemed like I could install the new card and keep in the old card too. I'll have the stock cards left over, I think its a GT120 with 512MB. Showing that if I just buy a stock PC card, it won't get the whole performance so I should buy it from macvidcards? Or can I just buy a regular one and get full performance? Does this issue only apply in Mac OS or Windows, toO? When I read 'no boot screen', does that mean refit won't show up either? Not a problem long as I can make windows default. Can you give an approximate percentage difference in performance? What's the best card for these computers? GTX 570 or GTX 680? I saw some folks saying 680 is actually worse performance for video editing, better for gaming. I know I've to upgrade to Mountain Lion to make these work and hope future OSes don't break support. One of the machines is going to be turned into windows only (Mac OS will be installed, just not used) and the other will likely be dual boot or Mac only. I'd like to know which is the best card for me in this scenerio: I've two 2009 dual-proc Mac Pros mostly used for video editing.

I've tried sifting through the threads on this but seem to be getting more confused.

Best video card for mac pro early 2009